This invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to toner compositions, wherein more than one polymer, including at least one wax component, can be selected. In embodiments, the present invention is directed to negatively charged toner compositions comprised of polyester resins, especially certain crosslinked extruded polyesters, wax, compatibilizer, pigment, and surface additives of, for example, metal salts of fatty acids, silica particles, especially fumed silica particles available from Cabot Corporation, metal oxides like titanium dioxide, and wherein the developer is comprised of toner and carrier coated with a polymer, such as polymethylmethacrylate or mixture of polymers, such as polymethylmethacrylate (PMMA) and FPC461.RTM., a fluorocopolymer obtained from Occidental Chemical, and wherein the carrier coating contains a conductive component like carbon black, such as VULCAN 72R.RTM. carbon black available from Cabot Corporation. In embodiments, the wax component possesses a low molecular weight, M.sub.w, average, such as from about 1,000 to about 20,000, and includes polyethylene wax and polypropylene wax, and the compatibilizer is an alkylene-glycidyl methacrylate polymer as illustrated in U.S. Pat. No. 5,368,970, the disclosure of which is totally incorporated herein by reference. The toner and developer compositions of the present invention are useful in a number of known electrostatographic imaging and printing systems, such as xerographic imaging and printing systems including printing methods with lasers.
In embodiments, the conductive magnetic brush developers of the present invention can be selected for hybrid jumping development, hybrid scavengeless development, and similar processes, reference U.S. Pat. Nos. 4,868,600; 5,010,367; 5,031,570; 5,119,147; 5,144,371; 5,172,170; 5,300,992; 5,311,258; 5,212,037; 4,984,019; 5,032,872; 5,134,442; 5,153,647; 5,153,648; 5,206,693; 5,245,392 and 5,253,016, the disclosures of which are totally incorporated herein by reference. The aforementioned developers, which can contain a negatively charging toner are suitable for use with laser or LED printers, discharge area development with layered flexible photoconductive imaging members, reference U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference, and organic photoconductive imaging members with a photogenerating layer and a charge transport layer on a drum, light lens xerography, charged area development on, for example, inorganic photoconductive members such as selenium, selenium alloys like selenium, arsenic, tellurium, hydrogenated amorphous silicon, trilevel xerography, reference U.S. Pat. Nos. 4,847,655; 4,771,314; 4,833,540; 4,868,608; 4,901,114; 5,061,969; 4,948,686, and 5,171,653, the disclosures of which are totally incorporated herein by reference, full color xerography, and the like, reference for example the Xerox Corporation 4850.RTM.. In embodiments, the developers of the present invention are preferably selected for imaging and printing systems with conductive magnetic brush development as illustrated, for example, in U.S. Pat. No. 4,678,734, the disclosure of which is totally incorporated herein by reference, and wherein there is enabled in embodiments high development levels, development to substantially complete neutralization of the photoreceptor image potential, development of low levels of image potentials, and increased background suppression. Further, the toners of the present invention are free of charge enhancing additives like cetyl pyridinium chloride, thereby minimizing or avoiding environmental problems.
With the developers of the present invention, low melting polyesters are preferably selected as the toner resin permitting, for example, lower fuser energies; the toner size is, for example, from about 7 to about 15 and preferably 9 microns in average volume diameter as determined by a Coulter Counter, and the toner possesses narrow GSD in embodiments, for example about 1.3. Additionally, the developers of the present invention in embodiments enable high levels of toner flow, for example from about 7 to about 10 grams per minute; rapid admix of, for example, about 30, and preferably 15 seconds or less, as determined by the charge spectrograph; a toner triboelectric charge of from about -12 to about -20; and high levels of developer conductivity, for example 10.sup.-7 to 10.sup.-8 (ohm-cm).sup.-1 at a 3 percent toner concentration. Moreover, in embodiments the surface additive of a fatty acid salt like zinc stearate functions primarily as a conductivity component and the fumed silica functions primarily as a flow aid, toner blocking avoidance component, and for assistance in achieving excellent admix characteristics. The third additive of metal oxides, like titanium dioxide, in the surface mixture assists in achieving a combination of excellent toner flow, superior admix, and acceptable blocking characteristics, and moreover, the three surface mixture assists in controlling the tribocharge of the toner, especially with 0.6 weight percent of titanium dioxide P25.RTM. available from Degussa Chemicals, 0.6 weight percent of the fumed silica TS530.RTM. available from Degussa Chemicals, and zinc stearate present in an amount of 0.3 weight percent.
Toner and developers with toner additives like wax and surface additives of, for example, metal oxides and colloidal silicas are known. Toners with polyesters, including extruded polyesters, are also known, reference U.S. Pat. No. 5,227,460, the disclosure of which is totally incorporated herein by reference. In U.S. Pat. No. 4,795,689, there is disclosed an electrostatic image developing toner comprising as essential constituents a nonlinear polymer, a low melting polymer, which is incompatible with the nonlinear polymer, a copolymer composed of a segment polymer, which is at least compatible with the nonlinear polymer, and a segment polymer, which is at least compatible with the low melting polymer, and a coloring agent, see the Abstract, and columns 3 to 10 for example; and U.S. Pat. No. 4,557,991 discloses a toner for the development of electrostatic images comprised of a certain binder resin, and a wax comprising a polyolefin, see the Abstract; also see columns 5 and 6 of this patent and note the disclosure that the modified component shows an affinity to the binder and is high in compatibility with the binder, column 6, line 25.
Developer and toner compositions with certain waxes therein, which waxes can be selected as a component for the toners of the present invention, are known. For example, there are illustrated in U.K. Patent Publication 1,442,835, and a number of corresponding U.S. Patents to Konica of Japan, the disclosures of which are totally incorporated herein by reference, toner compositions containing resin particles, and polyalkylene compounds, such as polyethylene and polypropylene, of a molecular weight of from about 1,500 to about 20,000, reference page 3, lines 97 to 119, which compositions prevent toner offsetting in electrostatic imaging processes. Additionally, the '835 publication discloses the addition of paraffin waxes together with, or without a metal salt of a fatty acid, reference page 2, lines 55 to 58. Also, in U.S. Pat. No. 4,997,739, there is illustrated a toner formulation including polypropylene wax (M.sub.w : from about 200 to about 6,000) to improve hot offset. In addition, many patents disclose the use of metal salts of fatty acids for toner compositions, such as U.S. Pat. No. 3,655,374, the disclosure of which is totally incorporated herein by reference. Also, it is known that the aforementioned toner compositions with metal salts of fatty acids can be selected for electrostatic imaging methods wherein blade cleaning of the photoreceptor is accomplished, reference U.S. Pat. No. 3,635,704, the disclosure of which is totally incorporated herein by reference. Additionally, there are illustrated in U.S. Pat. No. 3,983,045 three component developer compositions comprising toner particles, a friction reducing material, and a finely divided nonsmearable abrasive material, reference column 4, beginning at line 31. Examples of friction reducing materials include saturated or unsaturated, substituted or unsubstituted, fatty acids preferably of from 8 to 35 carbon atoms, or metal salts of such fatty acids; fatty alcohols corresponding to said acids; mono and polyhydric alcohol esters of said acids and corresponding amides; polyethylene glycols and methoxy-polyethylene glycols; terephthalic acids; and the like, reference column 7, lines 13 to 43.
Described in U.S. Pat. No. 4,367,275 are methods of preventing offsetting of electrostatic images of the toner composition to the fuser roll, which toner subsequently offsets to supporting substrates, such as papers, wherein there are selected toner compositions containing specific external lubricants including various waxes, see column 5, lines 32 to 45.
There are various problems observed with the inclusion of polyolefin or other waxes in toners. For example, when a polypropylene wax is included in toner to enhance the release of toner from a hot fuser roll, or to improve the lubrication of fixed toner image, it has been observed that the wax does not disperse well in the toner resin. As a result, free wax particles are released during the pulverizing step in, for example, a fluid energy mill and the pulverization rate is lower. The poor dispersion of wax in the toner resin and, therefore, the loss of wax will then impair the release function it is designed for. Scratch marks, for example, on xerographic developed toner solid areas caused by stripper fingers were observed as a result of the poor release. Furthermore, the free wax remaining in the developer will build up on the detone roll present in the xerographic apparatus causing a hardware failure.
All the problems mentioned above and others can be eliminated, or minimized with the toner compositions and processes of the present invention in embodiments thereof. The release of wax particles is, for example, a result of, for example, poor wax dispersion during the toner mechanical blending step. The wax additives should be dispersed well in the primary toner resin for them to impart their specific functions to the toner and thus the developer. For some of the additives, such as waxes like polypropylene VISCOL 550P.TM., that become a separate molten phase during melt mixing, the difference in viscosity between the wax and the resin can be orders of magnitude apart, thus causing difficulty in reducing the wax phase domain size. A more fundamental reason for poor wax dispersion is the inherent thermodynamic incompatibility between polymers. The Flory-Huggins interaction parameter between the resin and the wax is usually positive (repulsive) and large so that the interfacial energy remains very large in favor of phase separation into large domains to reduce interfacial area. Some degree of success has been obtained by mechanical blending of the toner formulation in certain types of mixers, such as the known Banbury mixer, where the temperature of melt can be maintained at a low level and polymer viscosities are not that far apart. However, it has been found difficult to generate an effective wax dispersion in compounding extruders where melt temperatures are typically higher. The inclusion of a compatibilizer of the present invention is designed to overcome the inherent incompatibility between different polymers, and, more specifically, between toner resin and wax, thus widening the processing temperature latitude and enabling the toner preparation in a large variety of equipment, for example an extruder. The improvement in thermodynamic compatibility will also provide for a more stable dispersion of secondary polymer phase, such as wax, in the host resin against gross phase separation over time. Also, with the present invention there are provided negatively charged toners that can be selected for discharged area development and other development processes as illustrated herein.
Illustrated in copending patent applications U.S. Ser. No. 331,444 and U.S. Ser. No. 331,441, the disclosures of which are totally incorporated herein by reference, are toners with surface additive mixtures of silica, polyvinylidene fluoride, a KYNAR.RTM., and strontium titanate.
Illustrated in copending patent applications U.S. Ser. No. 379,822, filed concurrently herewith, is a developer composition comprised of negatively charged toner particles comprised of crosslinked polyester resin particles, pigment particles, and a surface additive mixture comprised of metal salts of fatty acids in an amount of from about 0.2 to about 0.5 weight percent, and silica particles in an amount of from about 0.2 to about 0.5 weight percent; and carrier particles comprised of a core with a coating thereover containing a conductive component; U.S. Ser. No. 379,858, filed concurrently herewith, illustrates a developer composition comprised of negatively charged toner particles comprised of crosslinked polyester resin particles, pigment particles, and a surface additive mixture comprised of metal salts of fatty acids in an amount of from about 0.2 to about 0.5 weight percent, metal oxide particles in an amount of from about 0.3 to about 1 weight percent, and silica particles in an amount of from about 0.2 to about 0.5 weight percent; and carrier particles comprised of a core with a coating thereover containing a conductive component; and U.S. Ser. No. 379,224, filed concurrently herewith, illustrates an insulating developer composition comprised of resin particles, pigment particles, wax component particles, compatibilizer, and a surface additive mixture comprised of metal salts of fatty acids, silica particles, and metal oxide particles; and carrier particles comprised of a ferrite core with a polymer coating or mixture of polymer coatings; and wherein said developer is of a conductivity of from about 10.sup.-14 to about 10.sup.-16 (ohm-cm).sup.-1, the disclosures of which are totally incorporated herein by reference.